1. Field of the Invention
The invention relates to a machine-implemented method and an electronic device for presenting a dual-axis graph for a pair of data sets, in which adjustments are made to boundaries of one of two reference axes in a manner allowing for optimal comparison between the data sets.
2. Description of the Related Art
It is often desirable to present a pair of data sets on a single graph. Microsoft Office EXCEL® may be used for such a purpose. The graph of FIG. 1 is presented using Microsoft Office EXCEL®, and shows average educational expenditures for each child in the United States (in thousands of US dollars) and average SAT (Scholastic Aptitude Test) scores in the United States from 1980 to 1988. Due to the significant difference in scale between the two data sets, however, no meaningful comparison therebetween is possible using the graph of FIG. 1.
Other conventional graphing tools are available. However, all conventional graphing tools are deficient with respect to the manner in which boundaries of the two reference axes are selected. For example, assuming that the two reference axes are y-axes, if the boundaries of the left y-axis are set to be equal to the maximum and minimum values of one of the data sets, and the boundaries of the right y-axis are set to be equal to the maximum and minimum values of the other data set, although the fluctuations in the resulting curves for the two data sets are clearly visible, completely erroneous conclusions may be drawn from the resulting graph since such an approach of setting the boundaries of the two axes is arbitrary. That is, with such an approach, the boundaries are set for the two axes without taking into consideration any relation between the two data sets, leading to curves that may suggest correlations between the data sets where there are none or correlations which may be inaccurate.